


rewrite the rulebook

by nilchance



Category: Undertale (Video Game)
Genre: Adoptive family, Fluff, Found Family, Gen, Minor Mettaton/Papyrus, POV Second Person, Post-Undertale Pacifist Route, References to Undertale Genocide Route, sans as dad
Language: English
Status: Completed
Published: 2017-04-04
Updated: 2017-04-04
Packaged: 2018-10-14 22:49:24
Rating: General Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 2,795
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10545664
Author URL: https://archiveofourown.org/users/nilchance/pseuds/nilchance
Summary: Frisk calls Sans 'Dad'. Sans dodges. Things work out.





	

It’s been almost seven months since monsters left the underground, and there’s no good reason for your weird little group to all be crammed in one house. Okay, yes, at first humans were shitty about renting to monsters, and Frisk got a couple threats in the mail, and Papyrus fractured his arm, and Alphys had a bad depressive episode. But the excuses got smaller and smaller until they come down to this: if any of you really wanted to leave, you would’ve done it by now.

You asked Toriel once if it bothers her to be around so many people, after she lived by herself in the ruins for so long. If she ever wanted you all to get the hell out. She’d stared at you like you were crazy, then put her big hand on your shoulder. “My friend,” she’d said, “I’m not alone anymore. Neither are you and Papyrus. This is your home as long as you’d like, and you are always welcome here.”

You like Toriel’s house. It’s loud and chaotic. The air usually smells like baking things, and increasingly less like potential housefires. (Toriel takes no shit from Undyne about kitchen safety.) Papyrus and Undyne break a lot of furniture and the back yard is torn up from bones and spears hitting the ground. Alphys shows you a shitton of anime and you drink sake on the back porch when she’s too sad to talk. You’re around to help Frisk with their homework, and Frisk is around with their quiet understanding when your nightmares get too bad to sleep. You tell Toriel jokes until you’re both hoarse with laughter, leaning on the furniture to stay upright. The house is far enough from the city that the stars are clear and go on forever. 

You’ve never seen Papyrus so happy. That’d be enough on its own, really.

You’ve never seen Frisk so happy either, and that matters more to you every day. They ask you for hugs and they laugh at your jokes. They cling to you when they’re still shaking from nightmares. These days, they come to you with scraped knees as often as they go to Toriel. They look at you like they see every ding and dent in your busted soul and they love you anyway. 

Kind of hard to leave, after that.

***

Christmas comes around. If you thought the house was a circus before, it’s nothing to what happens when Papyrus and Toriel collaborate. The house is an explosion of lights, mistletoe, stockings and Christmas spirit, like you’re all living in the mutant lovechild of a Lowe’s and a craft store. It’s awesome.

Then, of course, every person Frisk knows has to be invited over for Christmas. There are still a lot of monsters with no blood family, after the war, and there are plenty of humans being shunned by their own kind for seeking peace. Frisk doesn’t want anyone to be alone, and none of you are good at refusing Frisk. 

Even Asgore is here, though he and Toriel are carefully never in the same room. Frisk bounces back and forth between them like a ping-pong ball, and they made sure to settle Asgore with Undyne so he’d stop looking like a kicked puppy. Undyne, Mettaton (on a surprise one-night engagement) and Papyrus are trying to teach him to play Guitar Hero. Asgore’s not bad at it, surprisingly, even though his hands are way too big for the keys. He’s almost smiling for real now.

Mettaton has his head on Papyrus’s shoulder, smiling like the cat who got the cream. Papyrus is blushing, all flustered, but looks real happy about it. It’s cute. It’s probably not going anywhere, but hey, you never know, and Papyrus deserves whatever happiness he can get. You make a note to tease the hell out of them about it later.

You’re good at schmoozing. Everybody’s friend, life of the party, etcetera. You drift back and forth between clumps of people, making jokes, introducing strangers and wandering off as soon as you think it won’t get awkward. You’re a goddamn delight.

(You’ve got a headache and you kind of want to join Alphys in hiding under her bed for a few hours. Every time you pass Grillby, he pours a new definitely non-virgin drink in your cup and stares intently until you drink it. Thank fuck for Grillby.)

After a while, you wash up on the couch like a shipwrecked sailor. Frisk is there, bright-eyed and wired, grinning at you. You grin back and firmly shove a bottle of water in their hands, followed by a cupcake that’s only a little smooshed from being in your pocket.

“What did the cake say to the kid?” When they raise their eyebrows, a silent ‘?’, you say, “You want a piece of me?”

They laugh and take a bite of the cupcake. Their hands are a little shaky, although that could be from too much signing instead of low blood sugar. They’re in their element, the sun that all of you revolve around. A lot of pressure for a ten year old. 

They’ve got frosting on their cheek. You lick your thumb and wipe the frosting off, like you used to do to Papyrus. 

(Okay, like you still sometimes do to Papyrus.)

Their smile goes softer. They bump their head into your head and sign, _Thanks, Dad._

When you were stabbed, it took a few seconds for the pain to hit. Realization is like that. You register first that the kid is looking at you sidelong, hopeful, their heart in their eyes. The way they look when they ask for something they don't expect to get.

Dad. Dad?

"Welp." You get up, hands shoved in your pockets. "Catch you later, kid."

Turning your back on someone speaking in hands is the height of rudeness. Gaster taught you better. But you turn from the kid before they can finish with your name sign, and you walk away. Out of the room, and then out of the house. You don't stop until you're in the back yard, past the point that you can hear the clamor of the party.

The night is sharp and very cold. There's snow thick on the ground. If you don't look up through the bare branches of the many fruit trees Asgore painstakingly planted for Frisk, you could think it was just another Christmas in Snowdin.

You look up. There are stars above, searing bright and real. All the books you read before coming through the barrier couldn't do them justice. It wasn't until you saw them that you could understand in your soul how they're really made of distant fire. Your fingers itch for your telescope.

The kid freed you all. The kid gave you stars, and libraries, and Papyrus driving down a long highway. The kid is all open hands and you're a closed fist.

It's funny. It's so fucking funny.

You stand out there for a while. You don't know how long. Your phone vibrates in your pocket a couple times, and you don't pick up. Your head is all noise without signal.

The ugly Christmas sweater Toriel knitted Papyrus has LED lights that flash. They cast green flickers across the snow as he trots out to you. Plenty of notice if you wanted to shortcut away. You don't.

When Papyrus reaches you, he hands over a mug of hot chocolate. It's still warm, a candy cane sticking out.

You take his offering with shaky hands. "Thanks, buddy. You didn’t have to come out and check on me. I’m fine.”

"What's wrong?" Straight to the point. That's Papyrus for you.

"There's nothing--" Papyrus narrows his eyes and you correct course. "Frisk called me 'dad'."

You're expecting him to laugh. Maybe to say something scathing about how he's been feeding your pet rock for years and you're nowhere near fit for taking care of a human. Maybe to flail a little about how ridiculous the very idea is.

Papyrus just looks at you, head tipped to one side. Trying to (heh) puzzle you out.

"I mean. Great sense of humor on that kid. Figured I'd give them a couple minutes to soak up the laughs before they. Y'know. Take it back."

When you were all underground and this Frisk fought Papyrus, the first two times Frisk got knocked down to one HP. You'd been creeping in the trees, because you had to know how it'd shake out one way or another, and you'd seen how stricken Papyrus looked when Frisk crumpled. How Papyrus had carefully gathered them up in his arms to carry them back to your shed. That's how Papyrus holds you now, like you're something little and wounded.

You're fine. You're still laughing, which means you're fine. But he exudes heat like a radiator and he's an excellent hugger, so you lean into him and tangle your fingers in his sweater. The mug drops to the snow and hemorrhages chocolate.

"I've always wanted to be an uncle," Papyrus says. "This is a wonderful present.”

It's like he put a knife through you. You hold him tighter, your voice an open wound as you say, "I can't."

Papyrus pulls back a little, far enough to look you in the face. Whatever he sees there hurts him, but he keeps smiling. "Why not? You already have been."

(You offer the kid mercy. They crawl into your arms, signing wretched apologies, weeping. You break their tiny neck. You taunt them as they die. You aren't sorry.)

"I'm not--" You stop, because you don't know how to even finish that sentence. Not a good person. Not worth it. Not strong enough. Not sure that if the resets kick in and you lose your brother and your kid, if you have to _kill_ your own kid, you can keep yourself from jumping off a fucking bridge every round instead. You're not a lot of things.

Papyrus frames your face in his hands so you have to look at him. "It's just a word, brother. Words are very important! But not as important as doing things. I believe in you."

"I don't."

"Then I will believe twice as hard! And if I believe in you, and Frisk believes in you, then that is a lot of extra belief left over." Papyrus beams. His eyes are shiny. "You already make embarrassing jokes like a human dad. It's like you've been training for years!"

"Maybe those were embarrassing older brother jokes."

"They're both," he says, instantly putting a bullet in your worries that he might get jealous. Unsurprising. Papyrus doesn't have a jealous bone in his body. (Heh.) (Fuck, you really do tell dad jokes.) "If you're worried because we didn't have a dad, we can get a book or something! I did a lot of research on how to uncle because I thought this very thing might happen. I’ll help you."

Aaand now you're leaking from the eyes. Great. "Thanks, Pap. I know you will."

"I know you know! We both know many things!" Gently, Papyrus takes his scarf and starts trying to wipe the tears off your face with it. Since he's still alive and wearing it, this is officially the nicest way you've ever cried all over that fucking scarf. "I'm very happy. Do you think I should get a different present?"

"What? No. You got them a great present. S'okay."

"Is it an uncle caliber present, though?" he frets.

"Dude. A chemistry set that could explode is classic uncle present. The kid'll love it." Toriel might murder you both, but that’s a problem for later. 

"Well. Good! I love them. And I love you. And everything will work out." Papyrus bumps his forehead against yours, the gentlest headbutt in the world. You haven’t done that since you were kids. Before Gaster unhappened. It’s weird and humid and so, so comforting. “I promise.”

You wince, automatically glancing around for an imploding Core or a murderous little kid. A disaster. 

Then again, you made a promise about Frisk, too. That worked out pretty okay.

Papyrus has that look that says he wants to ask but won’t. He knows you won’t answer, like the other million times he’s tried to figure out what’s wrong with you these days. Why you’re skittish and flinch at loud noises and freeze when anybody uses a knife. Why you have nightmares. You are guiltily grateful for the fact that the kid is waiting, a convenient excuse to change the subject.

Instead, he says, “I know you hate making promises, brother, but you’ll just have to accept one from me. The Great Papyrus always keeps his word.”

(He promised you once that he’d never leave you alone.)

“Yeah.” You chuck his chin. “I know, buddy. I believe you.”

“Good.” Satisfied, Papyrus bounds to his feet and offers you a hand up. “Now go in there and tell Frisk you’ll be their human dad. Do you want me to help?”

“You already did. I mean, you’re the coolest.” You let him pull you upright. “But I think this is something me and the kid oughta handle one-on-one, y’know?”

He nods sagely. “Then I’ll be on the other side of the room offering infinite moral support. Pick up your mug, Sans, you’re a dad now. You have to set a good example!”

You know when you’ve been beat. You pick up the mug and go back to the house.

The party's still going, a clamor of comfortable noise. Maybe nobody caught your freak-out, a hope that lasts just until you see Toriel sitting beside Frisk on the couch. Frisk is smiling away, signing to her, and Toriel isn't buying it.

Toriel glances at you sidelong as you approach, the teacher look that's quelled a thousand class clowns to silence. When you hunch a little, she gentles. Your poker face isn't what it used to be and you just bawled like a babybones in her yard, so she's probably not going to set you on fire.

"Hey, Tori," you say. "Undyne's talking about baking cookies. You might want to intervene before she roasts everybody's chestnuts."

Toriel turns her look over to Frisk, a silent question. When Frisk pats her hand, Toriel kisses their forehead. "I'll be right back, dear one."

And then Toriel's out, leaving the two of you alone. It's a rowdy room full of people with no volume control. Funny how it still feels like you're in a space of your own, staring each other down in a judgment hall.

_I'm sorry,_ Frisk says. Mostly they hold themselves so steady and adult that you can forget that they're still small. Ambassador Frisk, savior of the monster world, freezes up when Undyne slams a door, has screaming nightmares that give yours a run for their money, and never explains why they climbed a mountain that kills. They touch your hand and repeat, _I'm sorry._

If you ever find Frisk's human parents, they're going to have a bad time.

Whatever. Frisk is better off without them anyway.

"Nah." You sit down on the couch so you're on their level, keeping your body language easy. Hands in your pockets. "I'm sorry, kid. We freaked each other out a little."

_I shouldn't have called you that without asking._

"Eh, maybe. I needed a second to think about it." More like an hour, if you count the bit where you cried on Papyrus. "Are you sure, Frisk?"

_About you?_

"Yeah. Bunch of people around here that could be that for you. You could do a lot better. Hell, Undyne would make a great dad."

Frisk huffs a laugh. _Maybe. But she's not you. Are you worried because of timeline stuff?_

You shrug.

_But that wasn’t this you, or this me. You and me, we’re just us. You’ve never done anything bad to this me. I don’t think I’ve ever done anything bad to this you._ They hesitate, their expression one big question mark. _Am I wrong?_

The echo of your long-ago talk in the MTT lounge makes you smile. “Naw. We’re cool.” 

They relax. _We can pretend this never happened, if you want._

"We pretend a lot of things didn't happen, huh? Really takes it out of you. Turns out I'm too lazy for that." You spread your arms. "I don't care about papers or whatever, but I better get a #1 Bingo Dad mug out of this."

Their face lights up. Frisk flings themselves into your arms. It's not very comfortable for either of you, probably, because you're all bones, but they snuggle in.

Across the room, Papyrus gives you a beaming thumbs-up. Mettaton is perched on his lap.

_Thanks,_ Frisk tells you. _I'm glad you're here._

"Hi, glad you're here," you tell them. "I'm Dad."

**Author's Note:**

> "But you had to come along, didn't you?  
> Rev up the crowd, rewrite the rule book  
> Where do I go when every 'no' turns into 'maybe'?"  
> \- Stray Italian Greyhound, Vienna Teng


End file.
